Rhodium(I) carbonyl complexes of tetradentate chalcogen functionalized phosphines, [P′(X)(CH2CH2P(X)Ph 2)3] {X = O, S, Se}: Synthesis, reactivity and catalytic carbonylation reaction

Article abstract of DOI:10.1016/j.jorganchem.2011.07.014

The reaction of [Rh(CO)₂Cl]₂ with 0.5 mol equivalent of the ligands [P^′(X)(CH₂-CH₂P(X)Ph ₂)₃](P^′P₃X₄) {where X = O(a), S(b) and Se(c)} affords tetranuclear complexes of the type [Rh ₄(CO)₈Cl₄(P^′P ₃X₄)] (1a-1c). The complexes 1a-1c have been characterized by elemental analyses, mass spectrometry, IR and multinuclear NMR spectroscopy, and the ligands b and c are structurally determined by single crystal X-ray diffraction. 1a-1c undergo oxidative addition (OA) reactions with CH ₃I to generate Rh(III) oxidised products. Kinetic data for the reaction of 1a and 1b with excess CH₃I indicate a pseudo first order reaction. The catalytic activity of 1a-1c for the carbonylation of methanol to acetic acid and its ester show a higher Turn Over Frequency (TOF = 1349-1748 h^-1) compared to the well-known species [Rh(CO)₂I ₂]^- (TOF = 1000 h^-1) under the similar experimental conditions. However, 1b and 1c exhibit lower TOF than 1a, which may be due to the desulfurization and deselinization of the ligands in the respective complexes under the reaction conditions.

Full text of DOI:10.1016/j.jorganchem.2011.07.014

Journal of Organometallic Chemistry 696 (2011) 3279e3283
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Note
Rhodium(I) carbonyl complexes of tetradentate chalcogen functionalized
phosphines, [P0(X)(CH2CH2P(X)Ph2)3] {X ¼ O, S, Se}: Synthesis, reactivity
and catalytic carbonylation reaction
Biswajit Deb a, Podma Pollov Sarmah a, Kokil Saikia a, Amy L. Fuller b, Rebecca A.M. Randall b,
,
Alexandra M.Z. Slawin b, J. Derek Woollins b, Dipak Kumar Dutta a
*
a Materials Science Division, Council of Scientific and Industrial Research, North East Institute of Science and Technology, Jorhat 785006, Assam, India
b School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, UK
a r t i c l e i n f o
a b s t r a c t
The reaction of [Rh(CO)2Cl]2 with 0.5 mol equivalent of the ligands [P0(X)(CH2eCH2P(X)Ph2)3](P0P3X4)
{where X ¼ O(a), S(b) and Se(c)} affords tetranuclear complexes of the type [Rh4(CO)8Cl4(P0P3X4)]
(1ae1c). The complexes 1ae1c have been characterized by elemental analyses, mass spectrometry, IR
and multinuclear NMR spectroscopy, and the ligands b and c are structurally determined by single crystal
X-ray diffraction. 1ae1c undergo oxidative addition (OA) reactions with CH3I to generate Rh(III) oxidised
products. Kinetic data for the reaction of 1a and 1b with excess CH3I indicate a pseudo first order
reaction. The catalytic activity of 1ae1c for the carbonylation of methanol to acetic acid and its ester
show a higher Turn Over Frequency (TOF ¼ 1349e1748 hꢀ1) compared to the well-known species
[Rh(CO)2I2]ꢀ (TOF ¼ 1000 hꢀ1) under the similar experimental conditions. However, 1b and 1c exhibit
lower TOF than 1a, which may be due to the desulfurization and deselinization of the ligands in the
respective complexes under the reaction conditions.
Article history:
Received 4 May 2011
Received in revised form
13 June 2011
Accepted 5 July 2011
Keywords:
Rhodium
Carbonyl complex
Chalcogen donor
Functionalized phosphine
Carbonylation
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
to their importance in catalytic reactions [26e30]. For instance, OA
of CH3I to a square planar d8 complex is an important step in the
Tertiary phosphines functionalized with chalcogen donors like
oxygen [1e4], sulphur [5e9] and selenium [10,11] containing ‘soft’
phosphorus and ‘hard’ oxygen donors or ‘soft’ phosphorus and
relatively less ‘softer’ sulphur and selenium donor ligands with
rhodium catalyzed Monsanto’s process for acetic acid production
[31e33] and therefore the major focus has been made on the design
of catalysts for the improvement of this reaction. For this purpose,
considerable efforts have been made to improve the catalyst used
in Monsanto’s process i.e. [Rh(CO)2I2]ꢀ by incorporating different
ligands into its coordination sphere [3,7,11e14,21,34e42]. Thus, as
a part of our ongoing research activities [3,6,8,11,12,20e22,41e43],
herein we report synthesis, reactivity and catalytic carbonylation of
rhodium(I) carbonyl complexes containing P0P3X4, where X ¼ O(a),
S(b) and Se(c), as coordinating ligands. The X-ray structural char-
acterization of [P0P3S4](b) and [P0P3Se4](c) and the donor effects of
the ligands aec on the nucleophillicity of the metal centre have also
been demonstrated.
distinctly different p-acceptor strength [1] form a variety of metal
complexes due to their different bonding abilities. Recently, interest
in phosphorus chalcogenides has increased significantly since
ligands of these types may be effective in promoting catalysis at
metal centres [1e16]. Following this interest, the potential poly-
dentate phosphines such as tridentate, tetradentate or hexadentate
have been synthesized and their coordination chemistry and
reactivity are intensively examined [17e20]. Metal complexes of
multidentate phosphine chalcogen donor ligands also play an
important role on the stability and reactivity of the metal
complexes [3,8,11e16,21e25].
2. Results and discussion
The activation of small molecules by metal complexes through
OA reactions has been extensively investigated in recent years due
2.1. Synthesis and characterization of aec
Three chalcogen functionalized tetradentate ligands [P0(O)-
(CH2CH2P(O)Ph2)3] (a), [P0(S)(CH2CH2P(S)Ph2)3] (b) and [P0(Se)-
(CH2CH2P(Se)Ph2)3] (c) have been synthesized by oxidation of P0P3
* Corresponding author. Tel.: þ91 376 2370081; fax: þ91 376 2370011.
E-mail address: dipakkrdutta@yahoo.com (D.K. Dutta).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.07.014

3280
B. Deb et al. / Journal of Organometallic Chemistry 696 (2011) 3279e3283
with stoichiometric quantity of H2O2, elemental sulphur and
elemental selenium respectively [21e23]. The IR spectra of aec
exhibit characteristic bands at around 1174, 611e621 and
533e540 cmꢀ1 respectively, for the corresponding functional
groups P]O, P]S and P]Se. The 31P NMR spectra of aec show
2.2. Synthesis and characterization of 1ae1c
The dimeric precursor [Rh(CO)2Cl]2 reacts with 0.5 mol equiv-
alents of the ligands (aec) [Rhodium : Ligand ¼ 4:1] in CH2Cl2 to
afford complexes of the type [Rh4(CO)8Cl4(P0P3X4)](1ae1c). The IR
chemical shifts in the range
d
35.3e45.09 and
d
42.69e55.44 ppm
spectra of 1ae1c exhibit multiple
1988e2081 cmꢀ1 indicating the formation of a multinuclear
rhodium (I) carbonyl species of [P0P3X4] ligands. The
(PeX) bands
n(CO) bands in the range
for P(V) and P0(V) respectively with relative intensity 3:1. The
appearance of downfield shift of P(III) in 31P NMR spectra, and
methylene and phenylic protons in 1H NMR spectra compared to
the non-functionalized P0P3 analogue indicating the formation of
P0P3X4. In addition to the spectroscopic studies, the ligands aec
have also been characterized by elemental analyses and mass
spectrometry along with the single crystal X-ray structure deter-
mination of b and c (Fig. 1). The PeS (1.9555(16)e1.9584(15) Å) and
and PeSe (2.1055(15)e2.1112(14) Å) bond lengths (Fig. 1) are found
in the range similar to literature values [8,21,44e46]. Attempts to
substantiate the structure of a by single crystal X-ray structure
determination were not possible because no suitable crystals could
be obtained inspite of numerous attempts.
n
of the complexes at around 1149, 1186 (1a), 608, 582 (1b) and 522,
530 (1c) cmꢀ1 are lower in frequency than those of the corre-
sponding free ligands [
n
(PeX) ¼ 1174(a); 611, 621(b) and 533, 540
(c) cmꢀ1] confirming the formation of RheX bonds. The 31P {1H}
NMR spectra of 1ae1c show two distinct multiplets in the region
d
¼ 37.2, 56.5; 46.3, 52.3 and 37.4, 42.2 ppm respectively for two
different pentavalent P-atoms in the complexes. The intensity ratio
of two (PeX) bands in the IR spectra and the PeX chemical shifts
n
in 31P {1H} NMR spectra are found around 1:3, which indicate that
out of four rhodium centres, three having similar chemical envi-
ronment compared to the fourth one. The 1H NMR spectra of 1ae1c
show characteristic resonances for methylene and phenylic protons
in the range 2.04e2.80 and 7.48e8.04 ppm respectively. In the 13C
NMR spectra of 1ae1c, weak signals for the carbonyl carbons
appeared as broad singlet in the range 181.5e184.5 ppm. Elemental
analyses, estimation of rhodium and mass spectrometric studies of
the complexes support the observed molecular composition i.e.
[Rh4(CO)8Cl4(P0P3X4)]. The molecular structure of 1ae1c could not
be known as no suitable crystals for X-ray analysis could be
developed after several attempts. The estimation of rhodium
strongly supports the presence of four rhodium centres in a single
molecular unit. The electrospray mass spectrometric results
of 1ae1c show a cluster of peaks of low intensity centred at
m/z ¼ 1512.5 (1a), 1576.2 (1b) and 1762.9 (1c), which may be
assigned as [Rh4(CO)8Cl4(P0P3O4)]þ, [Rh4(CO)8-Cl4(P0P3S4)]þ and
[Rh4(CO)8Cl4(P0P3Se4)]þ respectively.
It is worth mentioning here that attempts to carry out the
reaction between [Rh(CO)2Cl]2 and aec with different Rh: ligand
stoichiometric ratio, always results in the formation of
[Rh4(CO)8Cl4(P0P3X4)] (Fig. 2) as evidenced by estimation of
rhodium, mass spectrometric and spectroscopic studies. However,
the reaction of [Rh(CO)2Cl]2 and non-functionalized phosphine,
P0P3 with variable Rh: ligand stoichiometric ratio generates
different composition of rhodium(I) carbonyl complexes of P0P3.
This fact along with a detail investigation of the coordination
behaviours of P0P3X4 ligands will be communicated in the form of
a full paper [47].
CO
Rh
CO
Cl
Cl
Ph2
P
Ph2
P
X
P
X
X
Rh
CO
CO
Cl
Rh
Ph2P
CO
X
CO
Cl
Rh
CO
OC
Fig. 1. X-ray crystal structures of b and c. Hydrogen atoms are omitted for clarity.
Selected bond lengths (Å), b: P(1)eS(1) 1.9555(16); P(2)eS(2) 1.9579(16); P(3)eS(3)
1.9584(15); P(4)eS(4) 1.9573(17). c: P(1)eSe(1) 2.1055(15); P(2)eSe(2) 2.1090(14);
P(3)eSe(3) 2.1106(14); P(4)eSe(4) 2.1112(14).
[X = O, S, Se]
Fig. 2. Plausible structure of [Rh4(CO)8Cl4(P0P3X4)](1ae1c).

B. Deb et al. / Journal of Organometallic Chemistry 696 (2011) 3279e3283
3281
Table 1
2.3. Reactivity of 1ae1c with methyl iodide
Results for carbonylation reaction of methanol.
The complexes 1ae1c undergo OA reactions with CH3I followed
by migratory insertion reaction to generate Rh(III)-acyl complexes
of the type [Rh4(CO)4Y4(COCH3)4I4(P0P3X4)] (2ae2c) [Where, Y ¼ Cl/
I] (Scheme 1). The IR spectra of the oxidized products show two
Catalyst
Precursor
[Rh(CO)2I2]ꢀc
1a
1b
1c
Time/h
Total
Conv.(%)
Acetic
Methyl
TOFb
(hꢀ1
acida (%)
acetatea
)
1
1
1
1
52.1
91.1
80.3
70.3
10.3
57.5
45.6
47.4
41.8
33.6
34.7
22.9
1000
1748
1541
1349
broad
n
(CO) bands in the range 2063e2071 and 1703e1726 cmꢀ1
characteristic of terminal and acyl carbonyl groups respectively. 31
P
a
{1H} NMR spectra of each of the oxidized products exhibit broad
multiplets indicating the presence of a mixture of isomers of
oxidative adducts. The possibility of different isomers may be due
to the presence of both iodide and chloride ligands, which are
expected to show some scrambling, giving the possibility of
different isomeric species with I/I ligands instead of I/Cl. The 1H
NMR spectra of the complexes 2ae2c display singlet resonances in
Yield of methyl acetate and acetic acid were obtained from GC analyses.
TOF ¼ [amount of product (mol)]/[amount of catalyst (Rh mol)]/time.
Formed from added [Rh(CO)2Cl]2 under catalytic condition [48].
b
c
the reaction mixture show multiple n(CO) bands indicating the
presence of a mixture of Rh(I) carbonyl and Rh(III) acyl complexes.
31P NMR spectra of the catalytic reaction mixture of 1b and 1c
shows an interesting weak doublet at around 21.5 ppm
(JPeRh ¼ 81.8 Hz) corresponding to RheP bond along with other
characteristic chemical shifts of RheXeP bonds. The appearance of
peak at 21.5 ppm due to RheP bond substantiates the partial
desulfurization and deselenization of ligands in the complexes 1b
and 1c respectively. However, in the complex 1a, the ligands
remained bound to the metal centre throughout the course of the
catalytic reactions. Thus, lower TOF of 1b and 1c over 1a may be due
to the partial desulfurization and deselenization of the ligands,
respectively under the reaction conditions to generate less active
RheP complexes.
the range
d 2.43e2.69 ppm suggesting the formation of eCOCH3
group including other characteristic bands of the ligands. The 13C
NMR spectra of 2ae2c exhibit bands in the range 202e206 ppm
characteristic to the acyl carbonyl group.
The kinetic measurement of OA reaction of the complexes 1a
and 1b with excess CH3I were monitored by following the decay of
lower frequency of n
(CO) bands in the region 2006e2008 cmꢀ1 by
using FT-IR spectroscopy. The rate constants for the OA reaction of
methyl iodide with 1a and 1b are measured and found as 2.3 ꢁ 10ꢀ4
and 4.5 ꢁ 10ꢀ4 sꢀ1, respectively. However, the kinetic study for the
OA reaction of methyl iodide to 1c could not be done due to the
partial deselenisation of the ligand in the presence of excess CH3I.
3. Conclusions
2.4. Carbonylation of methanol using 1ae1c as the catalyst
Three new rhodium(I) carbonyl complexes of the type
[{Rh(CO)2Cl}4(P0P3X4)] (1ae1c) have been synthesized and char-
acterized, and the ligands b and c are structurally determined by
single crystal X-ray diffraction. 1ae1c undergo OA reactions with
CH3I to generate Rh(III) oxidized products. Kinetics data for the
reaction of 1a and 1b with CH3I indicate a first order reaction. The
catalytic activity of 1ae1c for the carbonylation of methanol to
acetic acid and its ester show a higher TOF (1349e1748 hꢀ1) than
precursors
The results of carbonylation of methanol to acetic acid and
methyl acetate in the presence of 1ae1c as catalyst precursors are
shown in the Table 1. The precursor complexes 1ae1c show a total
conversion of 91.1, 80.3 and 70.3% of CH3OH at 130 ꢂ 2 ꢃC and
30 ꢂ 2 bar CO pressure with corresponding TOF of 1748, 1541 and
1349 hꢀ1. Under the similar experimental conditions, the well-
known catalyst, [Rh(CO)2I2]ꢀ generated in situ from [Rh(CO)2Cl]2
the well-known commercial species [Rh(CO)2I2]ꢀ (TOF ¼ 1000 hꢀ1
)
[48] shows only 52.1% total conversion with a TOF of 1000 hꢀ1
.
under the similar experimental conditions. In addition, the coor-
dination behaviour of P0P3 and P0P3X4 ligands and catalytic activity
by varying Rh/P ¼ X or Rh/P ratio may lead to interesting results.
Thus, the efficiency of the complexes depends on the nature of the
ligands and follows the order 1a > 1b > 1c > [Rh(CO)2Cl]2. It is
well-known that OA steps play a key role in enhancing the catalytic
efficiency of such reaction. As expected from higher OA reaction
rate of 1b over 1a, the former should act more efficiently than the
latter in the carbonylation reaction. But in practice, the reversed
situation was observed. In order to explain the above trend, each of
the catalytic reaction mixtures was analyzed by FT-IR and NMR
spectroscopy at the end of the catalytic reaction. The IR spectra of
4. Experimental
4.1. General
All solvents were distilled under N2 prior to use. RhCl3$xH2O
was purchased from M/S Arrora Matthey Ltd., Kolkota, India. The
ligand, [P0(CH2CH2PPh2)3] (P0P3) elemental sulphur and selenium
powder were obtained from M/S Aldrich, USA and used without
further purification. H2O2 was purchased from Ranbaxy, New Delhi,
India and the actual quantity of H2O2 was estimated before use.
Elemental analyses of C and H were performed on a Per-
kineElmer 2400 elemental analyzer. The analysis of rhodium was
carried out by gravimetric method (For details see Supplementary
materials). IR spectra (4000e400 cmꢀ1) were recorded in KBr
discs and CHCl3 on a PerkineElmer system 2000 FT-IR spectro-
photometer. The 1H, 13C and 31P NMR spectra were recorded at
room temperature in CDCl3 and CD3OD solution on a Bruker DPX-
300 Spectrometer and chemical shifts were reported relative to
SiMe4 and 85% H3PO3 as internal and external standards respec-
tively. Mass spectra of the complexes were recorded on ESQUIRE
3000 Mass Spectrometer. The carbonylation reactions of methanol
were carried out in a high pressure reactor (Parr-4592, USA) fitted
P/P3X4
CO
CO
OC
OC
Cl
Cl
[Rh4(CO)8Cl4(P/P3X4)]
Rh
Rh
DCM, stir.
Room temp.
[Rh : ligand = 4:1]
(1a-1c)
Rhodium chloro bridged dimer
CH3I
X
Ph2
Ph2P
X
P
X
[Rh4(CO)4Y4(COCH3)4I4(P/P3X4)]
P
[Y = Cl/I]
(2a-2c)
Ph2P
X
P/P3X4 :
X = O(a), S(b), Se(c)
Scheme 1. Synthesis and reactivity of 1ae1c.

3282
B. Deb et al. / Journal of Organometallic Chemistry 696 (2011) 3279e3283
with a pressure gauge and the reaction products were analyzed by
GC (Chemito 8510, FID).
analyses; Found (Cald. for C50H42Cl4O8Se4P4Rh4): Rh, 22.49 (23.33),
C, 33.30 (34.01), H, 2.08 (2.38). MS: m/z ¼ 1762.9 (Mþ).
4.4. Synthesis of [Rh4(CO)4Y4(COCH3)4I4(P0P3X4)](2) [X ¼ O(a), S(b)
and Se(c); Y ¼ Cl/I]
4.2. Synthesis of the ligands, [P0(X)(CH2CH2P(X)Ph2)3], where
[X ¼ O(a), S(b), Se(c)]
The Ligands [P0(O)(CH2CH2P(O)Ph2)3](a), [P0(S)(CH2CH2P(S)
Ph2)3](b) and [P0(Se)(CH2CH2P(Se)Ph2)3](c) were synthesized by
literature methods [21e23].
In 5 mL dichloromethane solution of 1ae1c (50 mg), CH3I
(3 cm3) was added drop by drop and the reaction mixture was
stirred at r.t. (25 ꢃC) for about 0.5e2 h. The colour of the solution
changed from yellowish red to dark reddish brown and the solvent
was evaporated under vacuum. The compounds so obtained were
washed with diethyl ether and stored over silica gel in a desiccator.
Analytical data for a: Yield: 85%; IR (KBr, cmꢀ1): 1174 [br,
n
(PeO)]. 1H NMR (CDCl3, ppm):
d
1.99, 2.42 (m, 12H, CH2),
d 7.40,
7.66 (m, 30H, Ph). 13C NMR (CDCl3, ppm):
d
19.2, 21.9 (m, CH2),
2a: IR (KBr, cmꢀ1): 2071 [
(PeO)]. 1H NMR (CDCl3, ppm):
2.52 (s, 12H, CH3),
7.45, 7.98 (m, 30H, Ph). 13C NMR (CDCl3, ppm):
22.8, 26.8 (m, CH2), 44, 50 (CH3), 129.9e138.5 (m, Ph), 180.7
36.3e38.5,
n
(CO)], 1726 [
n(CO)acyl], 1159, 1176
d
128.9e132.8 (m, Ph). 31P {1H} NMR (CDCl3, ppm): 35.3 [d, Pv,
d
53.64 [q, (P0)v, JPeP ¼ 50.8 Hz]. Elemental anal-
[n
d
2.09, 2.68 (m, 12H, CH2),
d
2.43,
JPeP ¼ 50.30 Hz],
d
d
yses; Found (Cald. for C42H42O4 P4): C, 67.98 (68.60), H, 5.48 (5.71).
d
d
d
d
MS: m/z ¼ 734.3 (Mþ).
(br, CO), 202.2 (br, COacyl). 31P {1H} NMR (CDCl3, ppm):
d
b: Yield: 92%; IR (KBr, cmꢀ1): 611, 621 [
n
(PeS)]. 1H NMR (CDCl3,
54.2e56.5 [m, PV]. Elemental analyses; Found (Cald. for
C54H54Cl4I4O12P4Rh4): Rh, 21.02 (19.79), C, 29.98 (31.15), H, 2.49
(2.60).
ppm):
(CDCl3, ppm):
d 2.12, 2.57 (m, 12H, CH2), d
7.42, 7.78 (m, 30H, Ph). 13C NMR
d
23.08, 26.44 (m, CH2), d
128.9e132.03 (m, Ph). 31P
{1H} NMR (CDCl3, ppm):
d
45.09 [d, Pv, JPeP ¼ 53.58 Hz],
d 55.44 [q,
2b: IR (KBr, cmꢀ1): 2065 [
(PeS)]. 1H NMR (CDCl3, ppm):
(s, 12H, CH3),
7.4, 8.05 (m, 30H, Ph), 13C NMR (CDCl3, ppm):
29.4 (CH2), 49, 53 (CH3), 123.3e135.9 (Ph), 181.5 (br, CO), 203.5
47.1e48.9, 53.8e55.7 [m,
n
(CO)], 1714 [
2.4, 2.9 (m, 12H, CH2),
n
(CO)acyl], 607, 574
2.56, 2.61
26,
(P0)v, JPeP ¼ 54.1 Hz]. Elemental analyses; Found (Cald for C42H42S4
P4): C, 62.58 (63.10), H, 5.08 (5.26). MS: m/z ¼ 799.1 (Mþ).
[n
d
d
d
d
c: Yield: 88%; IR (KBr, cmꢀ1): 533, 540 [ (PeSe)]. 1H NMR (CDCl3,
n
d
d
d
ppm):
(CDCl3, ppm):
d 2.28, 2.72 (m, 12H, CH2), d
7.44, 7.93 (m, 30H, Ph). 13C NMR
(br, COacyl). 31P {1H} NMR (CDCl3, ppm):
d
d
23.67, 26.94 (m, CH2), d P
128.95e131.73 (m, Ph). 31
PV]. Elemental analyses; Found (Cald. for C54H54Cl4I4O8S4P4Rh4):
Rh, 19.82 (19.20), C, 29.06 (30.22), H, 2.31 (2.51).
{1H} NMR (CDCl3, ppm):
d
37.34 [d, Pv, JPeP ¼ 55.8 Hz],
d
42.69 [q,
(P0)v, JPeP ¼ 55.3 Hz]. 77Se NMR (CDCl3, ppm):
d
ꢀ352.2 [d,
2c: IR (KBr, cmꢀ1): 2063 [
n
(CO)], 1703 [
(PeSe)]. 1H NMR (CDCl3, ppm):
2.3, 2.84 (m, 12H, CH2),
2.69 (s, 12H, CH3),
7.3, 7.89 (m, 30H, Ph), 13C NMR (CDCl3, ppm):
25.5, 30.2 (CH2), 46, 55 (CH3), 124.3e134.9 (Ph), 182.5 (br,
38.4e39.3,
n
(CO)acyl], 520, 527
JPeSe ¼ 729 Hz],
d
ꢀ368.1 [d, JPeSe ¼ 718 Hz]. Elemental analyses;
[n
d
d
2.49,
Found (Cald for C42H42Se4P4): C, 50.58 (51.09), H, 4.11 (4.26). MS:
d
m/z ¼ 986.7 (Mþ).
d
d
d
d
CO), 205.5 (br, COacyl). 31P {1H} NMR (CDCl3, ppm):
d
42.7e43.4 [m, PV]. Elemental analyses; Found (Cald. for
C54H54Cl4I4O8Se4P4Rh4): Rh, 15.62 (17.65), C, 28.03 (27.79), H, 2.85
(2.31).
4.3. Synthesis of the complexes [Rh4(CO)8Cl4(L)] (1),
L ¼ [P0(O)(CH2CH2P(O)Ph2)3](a), [P0(S)(CH2CH2P(S)Ph2)3](b) and
[P0(Se)(CH2CH2P(Se)Ph2)3](c)
[Rh(CO)2Cl]2 (100 mg) was dissolved in dichloromethane
(10 cm3) and to this solution, a stoichiometric quantity (Rh:L ¼ 1:4)
of the respective ligands were added. The reaction mixture was
stirred at room temperature (25 ꢃC) for about 30 min and the
solvent was evaporated under vacuum. The yellowish to reddish
brown coloured compounds so obtained were washed with
pentane as well as diethyl ether and recrystallized from DCM
solution. The compound was dried and stored over silica gel in
a desiccator.
Acknowledgements
The authors are grateful to Dr. P. G. Rao, Director, North East
Institute of Science and Technology, Jorhat-785 006, Assam, India
for his kind permission to publish the work. The Department of
Science and Technology (DST), New Delhi (Grant: SR/S1/IC-05/
2006) and Royal Society (UK) International Joint Project 2007/R2-
CSIR (India) joint research scheme are acknowledged for the
partial financial grant. The authors B. Deb (SRF) and P. P. Sarmah
(SRF) and KS (JRF) thank to CSIR and UGC, New Delhi respectively,
for providing the fellowships.
Analytical data for 1a: Yield: 85%; IR (KBr, cmꢀ1): 2006 (br),
2081(sh) [
2.04, 2.55 (m, 12H, CH2),
(CD3OD, ppm): 20.8, 22.8 (m, CH2),
(br, CO). 31P {1H} NMR (CD3OD, ppm):
n(CO)], 1149, 1186 [n
(PeO)]. 1H NMR (CD3OD, ppm):
d
d
7.55, 7.85 (m, 30H, Ph), 13C NMR
127.9e133.5 (m, Ph), 183.7
37.2, 56.5 [m, PV] Elemental
d
d
d
Appendix A. Supplementary material
d
analyses; Found (Cald for C50H42Cl4O12P4Rh4): Rh, 26.38 (27.21), C,
CCDC-748443(b) and 737947(c) contain the supplementary
crystallographic data for this paper. These data can be obtained free
of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
38.88 (39.67), H, 2.59 (2.78). MS: m/z ¼ 1512.5 (Mþ).
1b: Yield: 84%; IR (KBr, cmꢀ1): 2008 (br), 2079(sh) [
n
(CO)], 608,
2.32, 2.80 (m, 12H, CH2),
7.48, 7.84 (m, 30H, Ph), 13C NMR (CDCl3, ppm):
23.8, 27.1 (m,
CH2), 128.3e132.9 (m, Ph),
181.5 (br, CO). 31P {1H} NMR (CDCl3,
ppm):
46.3, 52.3 [m, PV]. Elemental analyses; Found (Cald for
582 [n d
(PeS)]. 1H NMR (CDCl3, ppm):
d
d
d
d
Appendix. Supplementary material
d
C50H42Cl4O8S4P4Rh4): Rh, 26.28 (26.11), C, 36.89 (38.06), H, 2.81
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.jorganchem.2011.07.014.
(2.66). MS: m/z ¼ 1576.2 (Mþ).
1c: Yield: 80%; IR (KBr, cmꢀ1): 1988 (br), 2065 (sh) [
n
(CO)], 522,
2.26, 2.72 (m, 12H, CH2),
7.44, 8.04 (m, 30H, Ph), 13C NMR (CDCl3, ppm):
23.9, 27.2 (m,
CH2), 129.3e133.8 (m, Ph),
184.5 (br, CO). 31P {1H} NMR (CDCl3,
ppm):
37.4, 42.2 [m, PV]. 77Se NMR (CDCl3, ppm):
ꢀ352.8
[d, JPeSe ¼ 730 Hz], ꢀ402.2 [d, JPeSe ¼ 1299 Hz]. Elemental
530 [n d
(PeSe)]. 1H NMR (CDCl3, ppm):
References
d
d
d
d
[1] A. Bader, E. Lindner, Coord. Chem. Rev. 108 (1991) 27e110.
[2] E. Lindner, K. Gierling, R. Fawzi, M. Steimann, Inorg. Chim. Acta 269 (1998)
13e22.
d
d
d

B. Deb et al. / Journal of Organometallic Chemistry 696 (2011) 3279e3283
3283
[3] B. Deb, D.K. Dutta, J. Mol. Catal. A 326 (2010) 21e28.
[4] V.V. Grushin, Chem. Rev. 104 (2004) 1629e1662.
[26] P.R. Ellis, J.M. Pearson, A. Haynes, H. Adams, N.A. Bailey, P.M. Maitlis, Organ-
ometallics 13 (1994) 3215e3226.
[5] J.W. Faller, S.C. Milheiro, J. Parr, J. Organomet. Chem. 693 (2008) 1478e1493.
[6] D.K. Dutta, P. Chutia, J.D. Woollins, A.M.Z. Slawin, Inorg. Chim. Acta 359 (2006)
877e882.
[7] L. Gonsalvi, H. Adams, G.J. Sunley, E. Ditzel, A. Haynes, J. Am. Chem. Soc. 124
(2002) 13597e13612.
[8] B. Deb, P.P. Sarmah, D.K. Dutta, Eur. J. Inorg. Chem. 11 (2010) 1710e1716.
[9] T.C. Blagborough, R. Devis, P. Ivison, J. Organomet. Chem. 467 (1994) 85e94.
[10] C. Cauzzi, M. Graiff, G.P. Lanfranchi, A. Tripicchio, Inorg. Chim. Acta 273 (1998)
320e325.
[11] D.K. Dutta, J.D. Woollins, A.M.Z. Slawin, D. Konwar, M. Sharma,
P. Bhattacharyya, S.M. Aucott, J. Organomet. Chem. 691 (2006) 1229e1234.
[12] D.K. Dutta, B. Deb, Coord. Chem. Rev. 255 (2011) 1686e1712.
[13] M.J. Baker, M.F. Giles, A.G. Orpen, M.J. Taylor, R.J. Watt, J. Chem. Soc. Chem.
Commun. 2 (1995) 197e198.
[27] M.V. Jimenez, E. Sola, M.A. Egea, A. Huet, A.C. Francisco, F.J. Lahoz, L.A. Oro,
Inorg. Chem. 39 (2000) 4868e4878.
[28] R.D. Adams, B. Captain, L. Zhu, J. Organomet. Chem. 693 (2008) 819e833.
[29] W.B. Tolman, E.I. Solomon, Inorg. Chem. 49 (2010) 3555e3556.
[30] R.H. Crabtree, The Organometallic Chemistry of the Transition Metals, second
ed. John Wiley and Sons, New York, 1994.
[31] A. Haynes, J. McNish, J.M. Pearson, J. Organomet. Chem. 551 (1998) 339e347.
[32] D. Forster, J. Am. Chem. Soc. 98 (1976) 846e848.
[33] D. Forster, Adv. Organomet. Chem. 17 (1979) 255e267.
[34] P.M. Maitlis, A. Haynes, G.J. Sunley, M.J. Howard, J. Chem. Soc. Dalton Trans. 11
(1996) 2187e2196.
[35] M.J. Howard, M.D. Jones, M.S. Roberts, S.A. Taylor, Catal. Today 18 (1993)
325e354.
[36] A.J. Pardey, C. Longo, Coord. Chem. Rev. 254 (2010) 254e272.
[37] Z. Freixa, P.C.J. Kamer, M.L. Anthony, P.W.N.M. van Leeuween, Angew. Chem.
Int. Ed. 44 (2005) 4385e4388.
[14] R.W. Wegman, A.G. Abatjoglou, A.M. Harrison, J. Chem. Soc. Chem. Commun.
24 (1987) 1891e1892.
[15] S.C. Milheiro, J.W. Faller, J. Organomet. Chem. 696 (2011) 879e886.
[16] J.W. Faller, T. Friss, J. Parr, J. Organomet. Chem. 695 (2010) 2644e2650.
[17] J.-C. Hierso, R. Amardeil, E. Bentabet, R. Broussier, B. Gautheron, P. Meunier,
P. Kalck, Coord. Chem. Rev. 236 (2003) 143e206.
[38] C.M. Thomas, R. Mafua, B. Therrien, E. Rusanov, H. Stoeckli-Evans, G. Süss-
Fink, Chem. Eur. J. 8 (2002) 3343e3352.
[39] F. Cherioux, C.M. Thomas, B. Therrien, G. Süss-Fink, Chem. Eur. J. 8 (2002)
4377e4382.
[18] C. Bianchini, J.A. Casares, R. Osman, D.I. Pattison, M. Peruzzini, R.N. Perutz,
F. Zanobini, Organometallics 16 (1997) 4611e4619.
[19] S.-I. Aizawa, K. Saito, T. Kawamoto, E. Matsumoto, Inorg. Chem. 45 (2006)
4859e4866.
[20] B.J. Sarmah, D.K. Dutta, J. Organomet. Chem. 695 (2010) 781e785.
[21] D.K. Dutta, J.D. Woollins, A.M.Z. Slawin, A.L. Fuller, B. Deb, P.P. Sarmah,
M.G. Pathak, D. Konwar, J. Mol. Catal. A 313 (2009) 100e106.
[22] B.Deb, B.J. Sarmah, B.J. Borah,D.K. Dutta,Spectrochim.ActaA72(2009)339e342.
[23] R. Colton, T. Whyte, Aust. J. Chem. 44 (1991) 525e535.
[24] M. Delferro, M. Tegoni, V. Verdolino, D. Cauzzi, C. Graiff, A. Tiripicchio,
Organometallics 28 (2009) 2062e2071.
[40] C.M. Thomas, G.S. Fink, Coord. Chem. Rev. 243 (2003) 125e142.
[41] D.K. Dutta, P. Chutia, B.J. Sarmah, B.J. Borah, B. Deb, J.D. Woollins, J. Mol. Catal.
A 300 (2009) 29e35.
[42] D.K. Dutta, J.D. Woollins, A.M.Z. Slawin, D. Konwar, P. Das, M. Sharma,
P. Bhattacharyya, S.M. Aucott, Dalton Trans. 13 (2003) 2674e2679.
[43] D.K. Dutta, B. Deb, B.J. Sarmah, J.D. Woollins, A.M.Z. Slawin, A.L. Fuller,
R.A.M. Randall, Eur. J. Inorg. Chem. 6 (2011) 835e841.
[44] J.A. Davies, S. Dutremez, A.A. Pinkerton, Inorg. Chem. 30 (1991) 2380e2387.
[45] P.W. Codding, K.A. Kerr, Acta Cryst. Sec. B 34 (1978) 3785e3787.
[46] P.W. Codding, K.A. Kerr, Acta Cryst. Sec. B 35 (1979) 1261e1263.
[47] B. Deb, D.K. Dutta, Unpublished work.
[25] J. Browning, G.W. Bushnell, K.R. Dixon, R.W. Hilts, J. Organomet. Chem. 434
(1992) 241e252.
[48] H. Adams, N.A. Bailey, B.E. Mann, C.P. Manuel, C.M. Spencer, A.G. Kent, J. Chem.
Soc. Dalton Trans. 2 (1988) 489e496.